There are calls for urgent reform of the smash repair industry after an ABC investigation revealed significant concerns that repairers linked to Australia's major insurers were putting vehicles back on the road with potentially deadly faults.

Consumer group Choice is warning the cost of home insurance could almost double in the decades ahead, with predictions extreme weather will become more common.

It has commissioned a study looking at the effect of climate change on the insurance market and has found insurers are rejecting customers in areas deemed too risky.

The report forecasts that premiums in vulnerable areas could rise by as much as 92 per cent over the period of a typical mortgage, which would likely reduce a home's value by 20 per cent compared to the rest of the market.

However, insurers say they cannot publish their future estimates on premium rises due to commercial sensitivities.

Wesfarmers expects to reap a profit of up to $335 million from the $1.01 billion sale of its insurance broking arm.

The Australian conglomerate, best known for its ownership of retail outlets including Coles and Bunnings, is selling its OAMPS businesses in Australia and the UK and Crombie Lockwood in New Zealand.

The buyer is Illinois-based and New York Stock Exchange-listed Arthur J. Gallagher & Co, one of the world's largest risk management and insurance broking companies, which employs over 16,000 people in 25 countries.